I don't want to sound mean, but you must research your purchases better than what you are doing now. Your tank is nowhere near able to support a sebae anemone and maroon clowns get big, mean and nasty. Both are poor choices for your tank.

Also, there is no guarantee any clownfish will choose to have a host anemone. They can just as easily decide to be hosted by a leather coral, mushroom coral, piece of live rock or even a powerhead.